noun. A type of falcon belonging to the genus Falco that is distributed worldwide. It is a fierce bird of prey measuring nearly 9" inches long with an impressive wingspan of 21". This bird is widely believed to have the most ass-kicking power per gram of any bird known to man. It has been known to prey on creatures weighing many times more than its own body weight.

"Holy shit!! that kestrel just killed an ate that entire pack of wolves!! Man, kestrels are so badass."